Trigonometric Equations Question 278
Question: If in any $ \Delta ABC $ , $ \cot \frac{A}{2},\cot \frac{B}{2},\cos \frac{C}{2} $ are in A. P. then
[MP PET 2003]
Options:
A) $ \cot \frac{A}{2}\cot \frac{B}{2}=4 $
B) $ \cot \frac{A}{2}\cot \frac{C}{2}=3 $
C) $ \cot \frac{B}{2}\cot \frac{C}{2}=1 $
D) $ \cot \frac{B}{2}\tan \frac{C}{2}=0 $
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Answer:
Correct Answer: A
Solution:
- Trick: Take $ A=B=C=60^{o}, $ then $ \cot \frac{A}{2},,\cot \frac{B}{2} $ and $ \cot \frac{C}{2} $ are in A.P. with common difference zero. Now option (b) satisfies.
BETA
